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diff --git a/Bachelor/CCNA4/en_CCNA4_v30/ch3/3_1_5/content.html b/Bachelor/CCNA4/en_CCNA4_v30/ch3/3_1_5/content.html new file mode 100644 index 0000000..cc9449e --- /dev/null +++ b/Bachelor/CCNA4/en_CCNA4_v30/ch3/3_1_5/content.html @@ -0,0 +1,169 @@ +<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns="http://www.w3.org/TR/REC-html40">
+
+<head>
+<meta http-equiv="Content-Language" content="en-us">
+<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
+
+
+
+<title>Content</title>
+<base target="_self">
+</head>
+
+<body background="../../images/bg.gif" topmargin="0" leftmargin="0" marginheight="0" marginwidth="0" onLoad="window.focus();" link="#808080" vlink="#808080" alink="#808080">
+
+<table border="0" cellpadding="0" cellspacing="0" width="100%">
+ <tr>
+ <td bgcolor="#336666" width="18" valign="top">
+ <img border="0" src="../../images/content_lines.gif" width="16" height="25">
+ <img border="0" src="../../images/transdot.gif" width="2" height="1"></td>
+ <td bgcolor="#336666"><b><font face="Arial" size="2" color="#FFFFFF">3</font></b><font face="Arial" size="2" color="#FFFFFF"><b>.1</b></font></td>
+ <td bgcolor="#336666"><img border="0" src="../../images/transdot.gif" width="10" height="1"></td>
+ <td bgcolor="#336666" width="100%"><strong>
+ <font face="Arial" size="2" color="#FFFFFF">Serial Point-to-Point Links</font></strong></td>
+ <td width="9" bgcolor="#336666"> </td>
+ </tr>
+ <tr>
+ <td bgcolor="#669999" height="25" width="18"> </td>
+ <td bgcolor="#669999" height="25"><b>
+ <font face="Arial" size="2" color="#FFFFFF">3.1.5</font></b></td>
+ <td bgcolor="#669999"><img border="0" src="../../images/transdot.gif" width="10" height="1"></td>
+ <td bgcolor="#669999" height="25" width="100%"><strong>
+ <font face="Arial" size="2" color="#FFFFFF">HDLC encapsulation</font></strong></td>
+ <td bgcolor="#669999" height="25" width="9"> </td>
+ </tr></table>
+
+<table border="0" cellpadding="0" cellspacing="0" width="95%" bordercolor="#111111">
+ <tr>
+ <td width="15"></td>
+ <td>
+
+ <font face="Arial" size="2" COLOR="#000000"> Initially, serial
+ communications were based on character-oriented protocols.
+ Bit-oriented protocols were more efficient but they were also
+ proprietary. In 1979, the ISO agreed on HDLC
+ as a standard bit-oriented data link layer protocol that encapsulates
+ data on synchronous serial data links. This
+ standardization led to other committees adopting it and extending the
+ protocol. Since 1981, ITU-T has developed a series of HDLC derivative
+ protocols. The following examples of derivative protocols are called
+ link access protocols:</font><ul>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> Link Access Procedure,
+ Balanced (LAPB) for X.25
+
+ </font>
+ </li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> Link Access Procedure on
+ the D channel (LAPD) for ISDN
+
+ </font>
+ </li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> Link Access Procedure for
+ Modems (LAPM) and PPP for modems
+
+ </font>
+ </li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> Link Access Procedure for
+ Frame Relay (LAPF) for Frame Relay</font></li>
+ </ul>
+ <p>
+ <font face="Arial" size="2" COLOR="#000000"> HDLC uses synchronous
+ serial transmission providing error-free communication between two
+ points. HDLC defines a Layer 2 framing structure that allows for flow
+ control and error control using acknowledgments and a windowing
+ scheme. </font><font face="Arial" size="2">Each frame has the same
+ format, whether it is a data frame or a control frame.</font></p>
+ <p>
+ <font face="Arial" size="2" COLOR="#000000"> Standard HDLC does not
+ inherently support multiple protocols on a single link, as it does not
+ have a way to indicate which protocol is being carried. Cisco offers a
+ proprietary version of HDLC. The Cisco HDLC frame uses a proprietary
+ ‘type’ field that acts as a protocol field. This field enables
+ multiple network layer protocols to share the same serial link. HDLC
+ is the default Layer 2 protocol for Cisco router serial interfaces.</font></p>
+ <p>
+ <font face="Arial" size="2" COLOR="#000000"> HDLC defines the
+ following three types of frame, each with a different control field
+ format: <img border="0" src="../../images/1.gif" align="absmiddle" width="12" height="12"></font></p>
+ <ul>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> <b>Information frames
+ (I-frames)</b> – Carry the data to be transmitted for the station.
+ Additional flow and error control - data may be piggybacked on an
+ information frame.</font></li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> <b>Supervisory frames
+ (S-frames)</b> – Provide request/response mechanisms when
+ piggybacking is not used.</font></li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> <b>Unnumbered frames
+ (U-frames)</b> – Provide supplemental link control functions, such
+ as connection setup. The code field identifies the U-frame type.</font></li>
+ </ul>
+ <p>
+ <font face="Arial" size="2" COLOR="#000000"> The first one or two bits
+ of the control field serve to identify the frame type. In the control
+ field of an Information (I) frame, the send-sequence number refers to
+ the number of the frame to be sent next. The receive-sequence number
+ provides the number of the frame to be received next. Both sender and
+ receiver maintain send and receive sequence numbers.
+
+ </font>
+ </p>
+ <p>
+ <TABLE bgcolor="#B0AFAF" width="95%" border="0" cellspacing="0" cellpadding="0">
+ <TR>
+ <TD valign="top">
+ <TABLE bgcolor="#669999" width="100%" cellspacing="0" cellpadding="0" border="0">
+ <TR>
+ <TD width="5">
+ <img border="0" src="../../images/lab_toplft.gif" width="116" height="23"></TD>
+ <TD><IMG alt="" height="1" width="3" src="../../images/s.gif"></TD><TD align="right" valign="top">
+ <IMG alt="" src="../../images/corner_ur_7.gif" width="7" height="7"></TD>
+ </TR>
+ </TABLE>
+
+ <TABLE bgcolor="#B0AFAF" width="100%" cellspacing="0" cellpadding="0" border="0">
+ <TR>
+ <TD>
+ <TABLE width="100%" cellpadding="2" cellspacing="0" border="0" bordercolor="#111111">
+ <TR>
+ <TD bgcolor="#ffffff" width="15"> </TD>
+ <TD bgcolor="#ffffff"><font FACE="Arial" SIZE="2" COLOR="#000000">
+ <p><font color="#808080">
+ <img border="0" src="../../images/links_icon.gif" width="25" height="25">
+ <b>Web Links</b></font></p>
+ </font><font FACE="Arial" SIZE="2" COLOR="#808080">
+
+ <p>Configuring Synchronous Serial Ports<p>
+ <a target="_blank" href="http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_configuration_guide_chapter09186a0080087283.html">
+ http://www.cisco.com/en/US/products/sw/
+ iosswrel/ps1828/ products_configuration_
+ guide_ chapter09186a0080087283.html</a></font></p>
+
+ <p>
+ <IMG alt="" height="2" width="1" src="../../images/s.gif"></p>
+ </TD>
+ </TR>
+ </TABLE>
+ </TD>
+ </TR>
+ </TABLE>
+ </TD>
+ </TR>
+ </TABLE><p>
+
+ <font face="Arial" size="2" COLOR="#000000">
+
+ </font>
+ </td>
+ </tr>
+ </table>
+
+</body>
+
+</html>
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